For example, if an application calls the Edit or AddNew member function and has not called Update, CancelUpdate cancels any changes made after Edit or AddNew was called.
If records are double-buffered (that is, automatic field checking is enabled), calling CancelUpdate will restore the member variables to the values they had before AddNew or Edit was called.
If there is no Edit or AddNew operation pending, CancelUpdate causes MFC to throw an exception. Call the GetEditMode member function to determine if there is a pending operation that can be canceled.
For related information, see the topic "CancelUpdate Method" in DAO Help.